This invention relates to the detection and counting of objects, such as symbols in drawings.
When searching an electronic drawing for symbols, the user may initially identify a particular symbol, then have a computer program search the drawing in order to count the number of parts represented by that symbol (e.g., to determine how many items or parts of a particular type need to be included in planning costs, ordered for installation, or for other purposes). In some cases, similar symbols that were not intended to be identified may be returned as part of the initial search and are often referred to as false positives.
For example, drawings often contain symbols that look similar, but may have variations in appearance or may have associated identifiers that distinguish parts from each other. This is illustrated in FIG. 1, where three groups of graphic symbols (representing electrical parts or items) are shown. Group 1 may illustrate data/telephone outlets, Group 2 may illustrate fluorescent light fixtures and Group 3 may illustrate electrical receptacles. These, of course, are only examples, since a typical construction drawing might have hundreds (or more) of different symbols. In each group, the symbols may vary in appearance (e.g., by shading) or have different identifiers (e.g., letters or numbers) that distinguish between similar symbols (and the parts they represent). As seen in FIG. 1, the same symbol may appear in some instances with identifiers inside the symbol, in other instances with an identifier adjacent or nearby the symbol, and in yet other instances without any identifier at all. Thus, each symbol may represent a general part (e.g., a light fixture), but the particular type of part (e.g., a type of light fixture) will depend on the identifier or variations in the symbol appearance. When searching for symbols in a drawing, the inclusion of similar symbols in search results (without taking into account variations in appearance or the existence of identifiers) may lead to the identification of unwanted symbols in the results.